In my above-referenced U.S. Pat. No. 5,337,588, I have described an electronic lock and key system, in which each of the respective lock and key devices is provided with on-board intelligence (its own control processor), with the lock supplying power for each of the lock and the key, and wherein communications between the lock and the key are effected by means of a secure bidirectional optical (infrared) communication link. An example of an electronic lock and key system with which the lock and key components described in my above-referenced co-pending application has particular utility is described in co-pending application Ser. No. 843,998 by C. Malinowski et al which is a continuation of application Ser. No. 596,100, filed Oct. 11, 1990, assigned to the assignee of the present application and the disclosures of which are herein incorporated. It should be observed, however, that the hardware structure of such a lock and key system is not limited to a particular type of application, but is intended to be useful in a variety of housing configurations.
A widely employed application where use of this new and improved functionality of such an electronic lock and key system is desired is in what is known as a `Eurocylinder` design, prevalent in residential buildings, offices and hotels throughout Europe. In accordance with the `Eurocylinder` standard, the lock hardware has a cylindrical unit or plug that is fitted into a main body housing, the main body being shaped and sized to be mounted into a support structure cavity, such as a mortise, of standardized dimensions for European mortise locks. The cylindrical plug and body are mounted to be generally flush with the support structure (e.g. door mortise). The plug has a keyway at one end and a lock operating element (in the form of a deadbolt-engaging cam) at the other end. To operate the lock, the blade of a mechanical key whose key pattern matches the actuator pattern of the lock's keyway is inserted into the keyway and the key is rotated. Rotating the key rotates the cylinder and thereby the cam, so as to operate the deadbolt.
Now although the electronic lock and key system described in my above-referenced application offers significantly improved security and flexibility as compared with the conventional Eurocylinder lock and key devices, and its replacement for the conventional mechanical design is desired, users of the improved system are faced with the fact that their mounting hardware is configured exclusively for a Eurocylinder-type device, so that to be widely accepted, any retrofit must conform with the dimensions of the standard.